Brachytherapy is a method of treating cancer by placing one or more radiotherapy sources in or by an area of tissue requiring treatment. Delivering radiation directly and accurately to the target treatment area may allow a clinician to administer higher doses of radiation while decreasing the impact on surrounding, healthy tissue.
In a typical brachytherapy treatment method, prior to treatment delivery, one or more conduits, for example, a brachytherapy applicator, a needle, a tube, or a catheter, is positioned within a target treatment area. The conduit is connected to a source of treatment, and a radiotherapy source is delivered from the treatment source and through the conduit into the treatment area. The conduits are positioned within the patient to deliver the radiotherapy source to suitable, pre-determined treatment locations. The treatment source may be a mechatronic or computerized device (e.g., an afterloader), or the treatment may be delivered manually, and the radiotherapy source may either be a small X-ray generating device, a high dose-rate radioactive source, or a low dose-rate radioactive source for use with longer, shorter, or even permanent dwelling times within the patient.
To increase the effectiveness of brachytherapy, clinicians aim to administer an optimal dosage of radiotherapy source to the target tissue. Following diagnosis, brachytherapy treatment may include multiple stages. Imaging of the patient anatomy and disease anatomy (e.g., tumor location, size, shape, density, orientation) may be analyzed to determine the appropriate regions to administer treatment to. During a treatment preparation and/or planning stage, the desired placement, positioning, and orientation of one or more conduits to deliver the treatment to these target treatment regions may then be determined. Additionally, one or more dwell positions (i.e., locations where the radiotherapy source will remain for a period of time) within each conduit may be mapped in order to achieve a desired dose distribution. During these stages, conduits, which may take the form of an applicator (e.g., having one or more individual conduit channels), needles, tubes, or catheters, may be inserted into a patient, and imaging may be used to confirm the position of the conduits. Next, during a treatment delivery stage, one or more radiotherapy sources may be delivered to the conduits, and the patient may undergo radiation treatment.
Movement or misalignment of one or more conduits may affect the amount of radiation treatment delivered to the target tissue. Misalignment could cause delivery of treatment to the wrong area or delivery of the wrong dosage of treatment to the target area. Yet, there is often no convenient way to verify positioning of the conduits after the treatment preparation/planning stage to confirm that the treatment will be delivered as planned.
For example, an applicator may be inserted into a patient for treatment planning, and medical imaging may be used to assess positioning of the conduits. Based on this information, a healthcare provider may determine the location of the dwell positions. Imaging and/or tracking devices and/or processing software may be used to assist with the treatment planning based on the location of the applicator within the body. Once treatment preparation and planning are complete, the patient may be moved into a different room for treatment delivery or otherwise prepared for treatment delivery. The treatment delivery room may include shielding to accommodate use of radioactive materials and may not be compatible with the imaging and/or tracking devices used during treatment planning. Accordingly, the treatment delivery system (e.g., afterloader) may determine radiotherapy source positioning based on indirect measurements, such as the predetermined dwell positions, saved imaging data, the length of the conduits, the distance that the source has been inserted into the conduits, and the connection of transfer tubes to the conduits. Yet, inaccuracies may occur when relying on secondary measurements. For example, any snaking, bunching, or slack that may be created as a wire with a source or sensor is fed into the conduit may result in inaccurate determinations of how far the source or sensor has been inserted and where in the conduit it is located. Thus, following insertion of the conduit into the body for treatment planning purposes, the conduit may shift within the body, and current systems may not be able to directly determine spatial positioning of the conduit. Consequently, current systems may be unable to directly or accurately verify the ultimate location of the radiotherapy source when delivered to the conduit. Shifting of the conduit after the imaging during treatment planning or preparation may go undetected, resulting in inaccurate radiation treatment for the patient.
Additionally, it may be difficult or impossible to synchronize positioning data across the various systems, resulting in potential undetected discrepancies or inefficiencies. For example, treatment delivery systems, such as afterloaders, may use one-dimensional data, like dwell positions, the number of conduits, and/or the length of the conduits, to determine positioning. Image processing/planning software may use image data to create their own position definitions. Three-dimensional tracking systems, such as electromagnetic tracking, optical tracking, and other multiple degrees-of-freedom sensor systems may use references and may determine positioning based on relative measurements and/or calibration. Because each system measures positional information differently, it may be difficult, if not impossible, to merge or synchronize this data.
Further, current methods of position verification, including medical imaging (e.g., radiography, X-ray, MRI, ultrasound), electromagnetic tracking, optical shape sensing, or in vivo dosimetry may be expensive, complex, unwieldy, may disturb the workflow, or may cause harm or discomfort to the patient. Additionally, these devices may not be integrated into the treatment delivery system and consequently their feedback cannot be easily or safely used to interrupt or adjust treatment delivery if an inconsistency is detected as treatment occurs.
Additionally, multiple catheters or needles may be inserted into a patient or an applicator may include multiple conduit channels. Each conduit may have unique shapes, lengths, sizes, etc., and each conduit may need to be connected to an afterloader in a specific orientation in order to deliver the radiotherapy source to the target treatment location in accordance with the treatment planning. Unintentionally switching one or more transfer tubes when connecting the conduits to the afterloader for treatment delivery may thus result in wrong or inaccurate delivery of radiation to the patient.
Thus, there exists a need for improved brachytherapy position verification systems and methods capable of confirming the placement of conduits within the patient, for detecting human error in transfer tube connection, and/or for promoting accurate radiotherapy source positioning. There also exists a need for a user- and patient-friendly position verification system and method that is effective, affordable, integrated into the work flow, and/or able to synchronize data between one or more of the various treatment planning, treatment delivery, imaging, and/or tracking devices.